Process

ABSTRACT

A method of preparing a non-aqueous dispersion of CuPc which comprises milling crude CuPc in a high boiling liquid at a temperature from 50° to 150° C. in the presence of a polyester amine or polyesterammonium salt and a CuPc fluidising agent. Preferred polyesterammonium salt is obtainable by reacting polyhydroxystearic acid with 3-dimethylaminopropylamine quaternised with dimethylsulphate.

This application claims benefit of international applicationPCT/GB94/02786, filed Dec. 20, 1994.

The present invention related to a process for making a non-aqueousdispersion (NAD) of a copper phthalocyanine (CuPc) which is especiallysuitable for direct incorporation into a printing ink.

In order to disperse pigments uniformly in a non-aqueous mediumespecially designed dispersing agents are required to producedispersions having acceptable viscosity and stability properties, whichwhen incorporated into printing inks give inks with acceptable flowcharacteristics. Thus, GB 1,373,660 discloses polyesteramine dispersantsobtainable by reacting poly(hydroxycarboxylic acids) (hereinafter PHCA)with diamines, especially alkylenediamines, and salts thereof. GB2,001,083 discloses polyesteramine dispersants obtainable by reactingPHCA with poly(C₂₋₄ -alkyleneimine) (hereafter PAI) and salts thereof.U.S. Pat. No. 5,000,792 discloses polyesteramine dispersants obtainableby reacting 2 parts of PHCA with 1 part of a di-alkylenetriamine. NADcontaining high concentrations of pigment often exhibit high viscosityand are difficult to handle and formulate into inks and paints. It hastherefore been proposed to incorporate fluidising agents into such NAD'sas disclosed in GB 1,508,576 (U.S. Pat. No. 4,057,436).

Offset inks and varnishes are presently made by first converting crudeCuPc to pigmentary CuPc by salt milling in the presence of awater-miscible solvent such as ethylene glycol followed by washing withwater to form a press paste which is either (1) dried and dispersed inan aliphatic medium or oil and formulated into an ink or (2) flushedinto the aliphatic medium to make a "flush" colour which is thenincorporated into the aliphatic medium to form the printing ink orvarnish. The direct dispersion of crude CuPc into the aliphatic mediumis difficult to achieve and the salt grinding process is expensive andproduces an effluent which poses an environmental hazard. There is aclear advantage of avoiding salt milling by milling the crude CuPc inthe solvent medium itself.

It has recently been proposed, in U.S. Pat. No. 5,175,282, to mill crudeCuPc in 1 to 10% of an organic solvent at elevated temperature and thenheat the milled paste in an aqueous medium in order to obtain pigmentaryCuPc which when formulated in compositions such as surface coatings andprinting inks exhibits improved flow characteristics compared withcompositions containing dry-ground CuPc pigments.

It has now been found that brighter and greener shades of CuPc in inksand varnishes are obtainable in NAD if the crude CuPc is milled withdispersing agents in a non-aqueous solvent itself at a temperature above50° C.

Thus, according to the invention there is provided a method of preparinga NAD of CuPc which comprises milling crude CuPc in a high boilingliquid at a temperature from 50° to 150° C. in the presence of

a) a polyesteramine or polyesterammonium salt obtainable by the reactionof an amine with a PHCA of formula (1)

    Y--CO O--A--CO!.sub.n --OH

wherein

A is divalent hydrocarbyl;

Y is hydrogen or optionally substituted hydrocarbyl;

n is from 1 to 100; and

b) a CuPc fluidising agent.

The precise structure of the chain terminating group Y is not criticalprovided it is inert to the other components of the composition underthe normal processing conditions to which it is subjected. It ispreferably free from ionic and strongly polar groups and preferably hasa molecular weight of less than 300 and contains only C and H or C, Hand O atoms.

The optionally substituted hydrocarbyl group Y is preferably alkyl oralkenyl containing up to 35 carbon atoms, especially from 7 to 25, andmore especially from 7 to 20 carbon atoms such as heptyl, octyl,undecyl, lauryl, heptadecyl, heptadecenyl, heptadecadienyl, stearyl,oleyl, linoleyl or such a group substituted by a hydroxy, halo or alkoxygroup, especially C₁₋₄ alkoxy. Other values for Y include, C₄₋₈-cycloalkyl, such as cyclohexyl; polycycloalkyls, for example,polycyclic terpenyl groups which are derivable from naturally occurringacids such as abietic acid; aryl, such as phenyl; aralkyl, such asbenzyl and polyaryl, such as naphthyl, biphenyl, stilbenyl andphenylmethylphenyl. Such groups are preferably unsubstituted orsubstituted by a group selected from hydroxy, halogen and C₁₋₄ -alkoxy.Particularly preferred terminal groups Y--CO-- are 12-hydroxystearyl and12-hydroxyoleyl.

The divalent hydrocarbyl represented by A may be an aromatic, aliphaticor cycloaliphatic group. It is preferably an alkylene or alkenylenegroup, especially one containing from 4 to 25 carbon atoms with at least4 carbon atoms between the oxygen atom and carbonyl group. Preferably nhas a value of at least two. When n is greater than one, the groupsrepresented by A in the polyester chain O--A--CO!_(n) may be the same ordifferent. When the group A is an aliphatic chain containing nine ormore carbon atoms it is preferred that n is from 1 to 10, and especiallyfrom 1 to 6. When the group A is an aliphatic chain containing up toeight carbon atoms it is preferred that n is from 1 to 60. The groupsrepresented by A may carry other substituents which do not conferwater-solubility on the molecule, such as halogen and alkoxy. Preferredexamples of the group (--O--A--CO) are 12-oxystearyl, 12-oxyoleyl and6-oxycaproyl.

The PHCA of formula I is conveniently derived from a mixture of (i) asaturated or unsaturated aliphatic hydroxycarboxylic acid containingfrom 4 to 25 carbon atoms having at least 4 carbon atoms between thehydroxy and carboxyl groups or a cyclic precursor thereof, such as alactone and (ii) one or more aliphatic carboxylic acids of the formulaY-COOH, where Y is as hereinbefore defined. Examples of suitablehydroxycarboxylic acids and precursors are 12-hydroxystearic acid,12-hydroxy-9-oleic acid (ricinoleic acid), 6-hydroxycaproic acid andε-caprolactone Examples of suitable acids from which the end group--Y--CO-- is derivable, by reaction with a terminal hydroxy group on thepolyester chain, are lauric acid, palmitic acid, stearic acid and9-oleic acid and mixtures containing these acids which are derivablefrom natural products. Preferred PHCA's are poly(12-hydroxystearicacid), poly(ricinoleic acid) and poly(6-hydroxycaproic acid),hereinafter PHS, PR and PHC respectively. PHS is especially preferred.

The amine which reacts with the PHCA contains at least one group whichis reactable with a carboxylic acid group of the PHCA, and is preferablya hydroxy and especially an amino group which may be either primary orsecondary amino. The amine may contain both hydroxy and amino groups asin alkanolamines or it may contain only amino groups as inalkylenediamines or PAI.

A first preferred dispersant is a polyesteramine of formula (2):

    Y--CO O--A--CO!.sub.n --Z--R                               (2)

wherein

Y, A and n are as hereinbefore defined;

Z is a divalent bridging group; and

R is an amino or ammonium group.

The divalent bridging group, Z, is preferably of the formula (3) or (4):

    --NQ--L--(3);--O--L                                        (4)

wherein

Q is hydrogen or alkyl and L is an alkylene or hydroxyalkylene group,or, when (2) is of formula (3), N, Q and L, together with the group Rform a cycloheteroaliphatic group. The group Q preferably contains up to25 carbon atoms. The alkylene group which is, or which is present in,the group L preferably contains from 2 to 6 carbon atoms. Examples ofthe group represented by Q are methyl, ethyl, n-propyl, n-butyl andoctadecyl and examples of the group represented by L are --(CH₂)₂ --,--(CH₂)₄ --, --(CH₂)₆ --, and --CH₂ --CHOH--CH₂ -- and an example of thecycloheteroaliphatic bridging group is piperazin-1,4-ylene.

When the group R is an amino group, it may be a primary, secondary ortertiary amino group and is preferably of the formula (5): ##STR1##wherein T¹ and T² are independently hydrogen, C₁₋₂₂ -alkyl, substitutedC₁₋₂₂ -alkyl, aralkyl or cycloalkyl; or

T¹ and T² together with the nitrogen atom to which they are attachedform a 5- or 6- membered ring.

When T¹ or T² is alkyl, it is preferably C₁₋₆ -alkyl, such as methyl.When T¹, T² and the nitrogen atom form a ring it is preferablypiperidinyl, morpholinyl or especially an N-alkylpiperazinyl. When T¹ orT² is aralkyl, it is preferably benzyl.

When the bridging group Z together with R forms a cycloheteroaliphaticgroup, one of T¹ or T² is incorporated into the bridging group. Thus,the group --Z--R may be of the formula (6): ##STR2##

It is preferred that both T¹ and T² are other than hydrogen, so that Ris tertiaryamino.

When the group R is an ammonium group, it is preferably of the formula(7): ##STR3## wherein T³ is hydrogen, C₁₋₂₂ -alkyl, substituted C₁₋₂₂-alkyl, aralkyl or cycloalkyl; and

W is a colourless anion.

The polyesterammonium salt is conveniently formed from thepolyesteramine by reaction with an acid or quaterising agent.

The acids used to form the polyesterammonium salt may be inorganic ororganic and include hydrochloric, sulphuric, acetic, formic,methanesulphonic, benzenesulphonic and benzoic acids. Preferably, theanion is methanesulphonic acid.

Preferred quaterising agents are dialkyl sulphates where the alkylgroups contain from 1 to 4 carbon atoms. An especially preferredquaterising agent is dimethylsulphate.

The polyesteramine or polyesterammonium salt is obtainable by reactingat least one PHCA with an appropriate amine in a suitable solventfollowed by reaction with a salt or quaterising agent. Such compoundsmay be prepared by any of the processes described in GB Patent Nos.1,342,746, 1,373,660, EP 127,325 and EP 23387 and all such dispersantsare incorporated herein by reference.

Particularly useful effects have been obtained when the polyesteramineis obtained as a quaternary ammonium salt by reacting 2 moles of PHSwith 1 mole of 3-dimethylaminopropylamine and subsequently quaterisingwith dimethylsulphate (hereinafter Dispersant 1). Dispersant 1 may beprepared by the method in EP 23387.

A second preferred dispersant is obtainable by the reaction of a PHCA offormula I with a PAI to form a PAI derivative in which at least twoPHCA's are attached to each PAI chain. The PHCA is as describedhereinbefore.

The PAI may be linear or branched, but is preferably branched, with atleast 20% of the nitrogen atoms present as tertiary amino groups. Themolecular weight of the PAI is generally greater than 500, preferablygreater than 5,000 and especially greater than 10,000. The molecularweight is preferably less than 200,000, more preferably less than100,000 and especially less than 50,000.

A preferred PAI is polyethyleneimine (hereinafter PEI), The secondpreferred dispersant is obtainable by reacting up to 50 parts,preferably up to 30 parts, more preferably up to 10 parts and especiallyup to 5 parts of a PHCA with one part of a PAI wherein all parts are byweight.

The preparation of dispersants of this type are described in GB2,001,083 and all such dispersants are imported herein by reference.

A particularly useful dispersant of this type is that obtainable byreacting 3 parts of PHS with 1 part PEI having a molecular weight ofabout 20,000 (hereinafter Dispersant 2). Dispersant 2 may be prepared bythe method described for Agent C in GB 2,001,083 except that a PEI withMW of 20,000 is used in place of the PEI with MW of 50,000.

A third preferred dispersant is that obtainable by reacting a PHCA offormula I with an amine of formula (8) ##STR4## wherein R¹ and R² areeach independently C₂₋₆ -alkylene; and

R³ is C₁₋₂ -alkyl; and where 0.8 to 1.0 molar equivalents of the aminogroups are reacted with the PHCA.

Examples of amines of formula 8 are N,N-bis(aminoethyl)-methylamine;N,N-bis (aminopropyl)methylamine; N,N-bis(aminobutyl)methylamine;N,N-bis(aminoethyl)ethylamine; N,N-bis(aminopropyl)ethylamine;N,N-bis(aminobutyl)ethylamine andN-(aminomethyl)-N-(aminoethyl)-methylamine.

The preferred PHCA is PHS.

The preparation of compounds of this type are described in GB 5,000,792and all such dispersants are incorporated herein by reference.

The CuPc fluidising agent is preferably at least partially soluble inthe high-boiling liquid and comprises a substituted ammonium salt of aCuPc acid wherein there are from 19 to 60 carbon atoms contained in atleast 3 chains attached to the nitrogen atom of the substituted ammoniumion:

Preferably, the CuPc fluidising agent contains at least four organicchains attached to each nitrogen atom of each substituted ammonium ionand these chains preferably contain, in total, between 25 and 40 carbonatoms. It is further preferred that at least one and more preferably twoof the chains are alkyl or alkenyl groups containing at least 8 andpreferably at least 12 carbon atoms, especially those groups containingbetween 12 and 20 carbon atoms.

The CuPc acid may be any CuPc molecule containing --COCOH groups or moreespecially --SO₃ H groups which is capable of forming a salt with anamine or substituted ammonium salt to form the substituted ammonium saltof the CuPc acid. The CuPc acid is preferably mono- or disulphonic ormore especially a mixture thereof containing on average from 1.0 to 1.6and especially from 1.1 to 1.5 sulphonic acids for each CuPc molecule.

Examples of amines and substituted ammonium salts which may be used toform the CuPc fluidising agent are tertiary amines and quaternaryammonium salts such as N,N-dimethyloctadecylamine,cetyl-trimethylammonium bromide, didodecyldimethylammonium chloride anddioctadecyldimethylammonium chloride.

Alternatively, the amines or substituted ammonium salts may containpolyester chains such as the amine and amine salts of the dispersants asdescribed hereinbefore.

The amines and substituted ammonium salts may be cyclised wherein atleast two of the organic chains are linked to form a ring containing thenitrogen atom which will form the charge centre of the substitutedammonium ion. The ring or rings so formed may be aliphatic rings such aspiperidine or aromatic rings such as pyridine and as examples of suchamines or salts there may be mentioned N-cetylpiperidine.

One or more of the organic chains attached to the N-atom of the amine orsubstituted ammonium ion may be substituted by aromatic groups such asphenyl and substituted phenyl radicals which are free from acidic groupse.g. benzyldimethyloctadecylammonium chloride. Alternatively one or moreof the organic chains may contain other nonacidic substituents such ashydroxy groups e.g. octadecylbis(2-hydroxyethyl)amine, amino orsubstituted amino e.g. 3(N-octadecyl-N-hydroxyethylamino)propyl-N'N'bis(2-hydroxyethyl)amine thus forming polyamines to one ofthe N-atoms of which is attached at least 3 organic chains containing atotal of at least 16 carbon atoms.

The preparation of the CuPc fluidising agent is described in GB1,508,576(U.S. Pat. No. 4,057,436) and all such agents are importedherein by reference.

Particularly useful effects have been obtained when the fluidising agentis the dioctadecyldimethylammonium salt of a sulphonated CuPc containingan average of 1.3 sulphonic acid groups (hereinafter Fluidising Agent1). The preparation of this is described as Agent A of GB 1,508,576.

The high boiling liquid may be any of those commonly used in the tradefor making printing inks especially offset inks and varnishes. It may bealiphatic or aromatic in character and is preferably a mixture ofaliphatic and aromatic distillates where the latter is in the smallerproportion than the former. The aliphatic distillate is typically acoal-tar distillate and preferably has a boiling point between 200° and360° C. Typical specific gravities are from 0.75 to 0.85. The chemicalcomposition of such aliphatic distillates has not been preciselydetermined, but the MW of the components is typically between about 170and 320. Some of the aliphatic distillates contain small amounts ofaromatic components and this is especially preferred in the processaccording to the present invention. Examples of commercially availablehigh boiling aliphatic distillates are those available from Magie BrosOil Company, USA (e.g. MagieSol 47 and 52) and those available fromCarless Refining Ltd, UK under the Paraset trade mark (e.g. Paraset29L).

The high boiling aromatic distillate preferably has a boiling pointsimilar to that of the aliphatic distillate and also a specific gravitywhich is typically between 0.7 and 1.2. Examples of high boilingaromatic distillates include benzene substituted by aliphatic chainscontaining up to 30 carbon atoms, especially up to 20 carbon atoms.These aliphatic chains may be linear or branched. Other suitablearomatic distillates are esters obtainable from phthalic acid orphthalic anhydride such as dimethylphthalate and esters obtainable frombenzalmalonates such as diethylbenzalmalonate.

The process according to the present invention may be carried out in ahigh energy bead mill. Any bead mill commonly used in the trade may beused provided that in operation a temperature in excess of 50° C. isobtainable. This may be achieved by external heating with a heatedjacket or be exploiting the heat generated during operation of the mill.A suitable bead mill is a Netzsch LMJI mill. It is preferred thatmilling is carried out above 75° C. and especially above 90° C.

The diameter of the beads depends to a large extent on the type of millused. Thus, in an attritor bead mill which is open to the atmosphere andhas a low relative speed, the diameter of the beads is preferablygreater than 2 mm and also preferably less than 5 mm and especially lessthan 3 mm. However, in a Netzsch mill which is totally enclosed and hasa much greater relative speed, the diameter of the beads is preferablynot greater than 2 mm, more preferably less than 1 mm and especiallyless than 0.5 mm, for example 0.25 mm.

Milling of the crude CuPc is continued until the mean particle size isbelow 50 microns, preferably below 20 microns and especially below 10microns.

As noted hereinbefore, printing inks or varnishes obtained using theprocess of the present invention produce clear greenish blue shadeswhich are greener and brighter than those obtained when milling iscarried out at below 50° C. or by milling solely in a high boilingaliphatic distillate containing no high boiling aromatic distillate.However, the greenest and brightest shades are obtainable when millingis carried out in a high-boiling aliphatic distillate which alsocontains an aromatic distillate and at temperatures above 500° C. It hasalso been found that the amount of CuPc fluidising agent can bedecreased as the milling temperature is increased.

The NAD also preferably contains an alkyd resin to improve thecompatibility and stability of the NAD when let down into an ink orvarnish. The alkyd resin may be any suitable resin which is commonlyused in the trade, but is preferably a "long oil" alkyd resin obtainableby reacting a long chain saturated or unsaturated fatty acid with apolyol and a di- or tri-carboxylic acid or their anhydrides. Thecarboxylic acids are preferably aromatic in character, for examplephthalic acid or trimellitic anhydride. Preferred fatty acids are C₁₆₋₁₈-aliphatic acids which may be saturated or unsaturated.

The NAD typically contains at least 5%, preferably at least 10%, morepreferably at least 15% and especially at least 25% by weight CuPcrelative to the total weight of the NAD. It is also preferred that theNAD contains less than 70%, more preferably less than 60% and especiallyless than 45%-CuPc by weight relative to the total weight of the NAD.

It is also preferred that the NAD contains at least 0.5% dispersant,more preferably at least 1% and especially at least 2% by weight of theNAD. Although the amount of dispersant in the NAD can be the same as theamount of crude CuPc it is not generally necessary to use this amount.Consequently, it is preferred that the amount of the dispersant is lessthan 25%, more preferably less than 15% and especially less than 10% byweight of the NAD.

The CuPc fluidising agent is preferably at least 0.1%, more preferablyat least 0.3% and especially at least 0.5% by weight of the NAD.Typically, the fluidising agent is less than 10%, preferably less than5% and especially less than 3% by weight of the NAD.

The high boiling liquid is preferably at least 20%, more preferably atleast 30% and especially at least 40% by weight of the NAD. Typically,the distillate is less than 90%, preferably less than 60%, morepreferably less than 70% and especially less than 60% of the NAD. Thehigh boiling distillate may be aliphatic or aromatic in nature orpreferably a mixture of both. When the high boiling liquid is a mixtureof aliphatic and aromatic distillates in which the latter is the smallerproportion it preferably contains at least 0.1%, preferably at least0.3% and especially at least 0.5% aromatic distillate based on the totalweight of the NAD. It is also preferably less than 10%, more preferablyless than 7% and especially less than 5% by weight, of the NAD.

When the NAD contains an alkyd resin, the resin is typically at least0.1%, preferably at least 0.3% and especially at least 0.5% by weight ofthe NAD. The resin is preferably less than 10%, more preferably lessthan 7% and especially less than 5% by weight of the NAD.

As noted hereinbefore, the NAD prepared in accordance with the processof the present invention gives clearer and greener shades of CuPc in ahigh-boiling liquid than those obtained hitherto. The inventiontherefore also provides a composition obtainable by a process accordingto the present invention as described hereinbefore.

The NAD obtainable by the process of the present invention is suitablefor use in the formulation of printing inks, especially off-set inks,and varnishes to give a clear, bright greenish blue image.

The NAD made by the process according to the invention may be dilutedwith a solvent based ink or with a white ink and used directly forprinting. The ink may additionally contain any other adjuvants commonlyused in printing, particularly off-set printing. The present inventionalso provides a clear, bright greenish blue image by application of theNAD to a substrate.

The invention is now further described in the following examples whereall references to amounts are to parts by weight unless stated to thecontrary.

Preparation of Polyester A

A mixture of xylene (348 parts) and a commercial grade of12-hydroxystearic acid (3350 parts; having acid and hydroxyl values of182 mg.KOH/gm and 160 mg.KOH/gm respectively) is stirred for 22 hours at190° to 200° C., the water formed in the reaction being separated fromthe xylene in the distillate which is then returned to the reactionmedium. After 152 parts of water have been collected, the xylene isremoved by heating at 200° C. in a stream of nitrogen. The resultingpale amber coloured liquid has an acid value of 35.0 mgms/KOH/gm.

Preparation of Dispersant 1

A mixture of polyester A (320 parts), 3-dimethylaminopropylamine (10.2parts) and toluene (65 parts) was stirred under reflux and under acurrent of nitrogen using a Dean & Stark head to remove water. Thetemperature was raised to 165° C. and held at this temperature for 6hours. After cooling to 20° to 25° C. under nitrogen, an 87.6% solutionof the adduct was obtained.

226 parts of this adduct was stirred at 40° C. and dimethylsulphate (6.7parts added). An exotherm raised the temperature to 500° C. which wasfurther raised to 90° C. by external heating. After holding at 90° C.for a further 90 minutes the reaction mass was cooled to 20°-25° C. Nofree dimethylsulphate was detectable by gas/liquid chromatography. Thisis Dispersant 1.

Preparation of Dispersant 2

Hydroxystearic acid (159 parts) was polymerised by stirring at 170°-180°C. in the presence of tetrabutyltitanate (1 part) as catalyst under anitrogen atmosphere in a vessel equipped with a Dean and Stark separatoruntil the polymer has an acid value of about 35 mg KOH/gm.

Polyhydroxystearic acid (159 parts) prepared as above andhighly-branched polyethyleneimine (53 parts, Polymin ex BASF) werestirred at 120° C. under nitrogen for about 3 hrs until the product hadan acid value of 16-20 mg KOH/gm. On cooling, the product was obtainedas a brown gum.

Preparation of Fluidising Agent 1

To a slurry of 300 parts of a filter cake containing 85.6 parts ofcopper phthalocyanine sulphonic acid which contains, on average, 1.3sulphonic acid groups per copper phthalocyanine nucleus in 3,700 partsof water at 70°-75° C. was added 56 parts of triethanolamine followedgradually by 78.6 parts of a commercially available 75% solution inisopropanol of didodecyldimethylammonium chloride (Arquad 2C/75; Arquadis a Registered Trade Mark). When these additions are complete 50 partsof 34% acetic acid was added and the precipitate was filtered off,washed with water and dried. The product was sparingly soluble intoluene.

EXAMPLE 1

Crude CuPc (70 parts) and Fluidising Agent 1 (2 parts) was added to asolution of Dispersant 1 (8 parts), alkyd resin (10 parts; Terlon 3supplied by Lawters) and dodecylbenzene (6 parts) in an aliphatichigh-boiling distillate (104 parts; Paraset 29L as supplied by CarlessRefining Ltd, UK). The above mixture was milled together in a stainlesssteel attritor Model 01-HD (Union Process, Ohio, USA) containing 3 mmdiameter stainless steel balls (380 ml). The attritor was heated to 110°C. by passing steam through the water jacket and milling continued for18 hours at 400 rpm with a tip speed of 1.3 ms⁻¹.

COMPARATIVE EXAMPLE A

The procedure of Example 1 was repeated with the exception that millingwas carried out in the absence of dodecylbenzene using the Parasetaliphatic distillate alone (110 parts) and maintaining a temperature of45° C. throughout using external cooling.

EXAMPLE 2

Example 1 was repeated but maintaining a milling temperature of 70° C.throughout.

EXAMPLE 3

Example 2 was repeated except that the dodecylbenzene was replaced bythe same amount of dimethylphthalate.

EXAMPLE 4

Example 2 was again repeated except that the dodecylbenzene was replacedby the same amount of diethylbenzalmalonate.

EXAMPLE 5

Example 2 was repeated except that the dodecylbenzene was replaced bythe same amount of dimethylphthalate and dispersant 1 was is replaced bythe same amount of dispersant 2.

EXAMPLES 6 TO 10 AND COMPARATIVE EXAMPLE B

EXAMPLES OF NADs IN PRINTING INKS

The NADs of the above examples (1 part) was mixed with a white inkpreviously prepared from titanium dioxide pigment (18 parts, TioxideRCR2) Dispersant 1 (0.4 parts), zinc/calcium rosinate (5.4 parts, PexateRT3) and toluene (6.56 parts). The prepared ink was coated onto butakoncoated paper with a number 2 K-bar using an automatic coater (Model KCC202, RK Print-Coat Instruments, UK). After drying the colourco-ordinates of the various prints were measured using a Chroma MeterCR-221 (Minolta, UK). The results are given in Table 1 below which showthat the inks prepared by milling at temperatures above 70° C. andespecially those also containing an aromatic high-boiling distillateexhibit greener and clearer shades than those obtained by milling atlower temperatures and in the absence of the aromatic distillate.

                  TABLE 1                                                         ______________________________________                                        Example    NAD    L          a     b                                          ______________________________________                                        6          1      59.09      -15.93                                                                              -38.12                                     7          2      59.26      -14.95                                                                              -38.08                                     8          3      59.00      -15.41                                                                              -38.37                                     9          4      58.52      -15.33                                                                              -38.24                                     10         5      59.86      -15.14                                                                              -38.20                                     B          A      60.36      -14.81                                                                              -35.79                                     ______________________________________                                    

We claim:
 1. A method of preparing a non-aqueous dispersion of a CuPcwhich comprises milling crude CuPc in a high boiling liquid at atemperature from 50° to 150° C. in the presence ofa) a polyester amineor polyesterammonium salt obtained by the reaction of an amine with apolyhydroxycarboxylic acid of formula (1)

    Y--CO O--A--CO!.sub.n --OH                                 (1)

wherein A is divalent hydrocarbyl; Y is hydrogen or optionallysubstituted hydrocarbyl; n is from 1 to 100; and b) a CuPc fluidisingagent.
 2. A method according to claim 1 wherein thepolyhydroxycarboxylic acid is obtained from 12-hydroxystearic acid,ricinoleic acid, 6-hydroxycaproic acid or ε-caprolactone.
 3. A methodaccording to either claim 1 or claim 2 wherein the polyesteramine orpolyesterammonium salt is of formula (2)

    Y--CO O--A--CO!.sub.n --Z--R                               (2)

wherein Y, A and n are as defined in claim 1; Z is a divalent bridginggroup; and R is an amino or ammonium group.
 4. A method according toeither claim 1 or claim 2 wherein the polyesteramine is obtained fromthe reaction of a polyhydroxycarboxylic acid and a poly(C₂₋₄-alkyleneimine) wherein at least two poly hydroxycarboxylic acids areattached to each polyalkyleneimine chain.
 5. A method as claimed in anyone of claims 1 to 2 wherein the polyesterammonium salt is obtained byreacting 2 moles of polyhydroxystearic acid with 1 mole of3-dimethylaminopropylamine subsequently quaternised withdimethylsulphate.
 6. A method as claimed in any one of claims 1 to 2wherein the polyesteramine is obtained by reacting 3 parts ofpolyhydroxystearic acid with one part of polyethylenimine having a MW ofabout 20,000.
 7. A method as claimed in any one of claims 1 to 2 whereinthe fluidising agent is a substituted ammonium salt of a CuPc whereinthere are from 19 to 60 carbon atoms contained in at least 3 chainsattached to the nitrogen atom of the substituted ammonium ion.
 8. Amethod as claimed in claim 7 wherein the fluidising agent is thedioctadecyldimethylammonium salt of a sulphonated CuPc containing onaverage 1.3 sulphonic acid groups.
 9. A method as claimed in any one ofclaims 1 to 2 wherein the high boiling liquid is an aliphaticdistillate.
 10. A method as claimed in claim 1 or 2 wherein the highboiling liquid is a mixture of a major proportion of an aliphaticdistillate and a minor proportion of an aromatic distillate.
 11. Aprinting ink comprising a non-aqueous dispersion prepared by a methodaccording to any one of claims 1 to
 2. 12. A method of preparing anon-aqueous dispersion of a CuPc which comprises milling crude CuPc in ahigh boiling liquid comprising an aliphatic distillate at a temperaturefrom 50° C. to 150° C. in the presence of:(a) a polyester amine orpolyesterammonium salt obtained by the reaction of an amine with apolyhydroxycarboxylic acid of formula (1)

    Y--CO O--A--CO!.sub.n --OH                                 (1)

wherein A is divalent hydrocarbyl; Y is hydrogen or optionallysubstituted hydrocarbyl; n is from 1 to 100; and (b) a CuPc fluidisingagent.
 13. A method as claimed in claim 12 wherein the aliphaticdistillate contains 0.1 to 10% aromatic distillate based on the weightof the non-aqueous dispersion.
 14. A method as claimed in claim 1wherein the amount of CuPc in the non-aqueous dispersion is at least 5%and less than 70% by weight of the dispersion.
 15. A method as claimedin claim 1 wherein the milling is carried out above 75° C.